Phacoemulsification is a technique that has revolutionized modern eye cataract surgery. Using phacoemulsification, surgeons can remove cataracts by making only a small incision into the eye. The small incision renders sutures unnecessary and eliminates the need for general anesthesia. Most patients recover very quickly with little impairment or inconvenience.
Phacoemulsification devices work by using a handpiece with a needle at the tip that vibrates at an ultrasonic frequency to break apart and emulsify the cataract. This is typically done by selectively powering a plurality of piezoelectric elements disposed adjacent a horn (also known as a wave guide). Expansion and contraction of the piezoelectric elements causes the horn to vibrate, thus causing a needle at the end of the horn to vibrate.
A phacoemulsification handpiece essentially performs three tasks simultaneously. The tip of the needle vibrates at an ultrasonic frequency to break apart and emulsify the cataract. A saline solution is fed into the eye to irrigate and to keep the eye from collapsing, and an aspiration line removes liquid and emulsified pieces of the cataract. This maintains the anterior chamber of the eye and also cools the handpiece.
Phacoemulsification handpieces have been known since the 1960s. For example, U.S. Pat. No. 3,589,363 was obtained by Charles Kelman. Since then, many improvements have been made upon the initial device. Common current phacoemulsification handpieces consist of a an outer shell which is used as a handle, a needle which is used to break up the cataract, a horn and piezoelectric elements which are used to drive the needle and are held inside the outer shell and a plurality of fluid paths, one for aspiration and the other for irrigation. Examples of such phacoemulsification handpieces are disclosed in U.S. Pat. Nos. 5,178,605 and 5,453,087.
As with virtually any non-disposable medical device, contamination and sterilization issues are present. Because the fluid pathways are integral to the handpiece, the handpiece is contaminated with biological waste with each use. Thus, the entire handpiece must be cleaned carefully after each procedure to avoid any possible cross-contamination among patients. The handpiece must undergo a stringent sterilization after each phacoemulsification procedure, especially due to the increasing occurrence of difficult diseases to kill (e.g. Transmissible Spongiform Encephalopathies) and surgery complications potentially due to contaminants from surgical instruments (e.g. Toxic Anterior Segment Syndrome, TASS).
The sterilization procedure, while essential for patients' health, can lead to a reduction in the life of the handpiece because of the heat exposure and the difficulty in sealing the handpiece against the high temperature steam used in sterilizing. Because the handpieces are relatively expensive, reduced handpiece life can increase the cost of treating the cataract. Furthermore, the sterilization procedure takes a great deal of effort and time, and is not completely error-free. For example, TASS could be caused by cataract and lens debris which remains in the handpiece, even if the handpiece was sterilized. This may occur since the sterilization procedure relies primarily on heat and may not adequately flush the handpiece or may not flush the handpiece at all.
It would be advantageous to provide a phacoemulsification system which did not require complete sterilization of the handpiece as previously done. Thus, it is desired to provide a phacoemulsification handpiece with removable, disposable or limited use fluid pathways for potentially contaminated fluids. These connections could be disposed of after each procedure, thus reducing cleaning effort and time, reducing the risk of possible cross-contamination. Such a handpiece would benefit from an increased lifespan, since the frequency of sterilization of the handpiece could be reduced and the sterilization procedure is harmful to the handpiece.
In additional to the above, one common concern with phacoemulsification handpieces is they have traditionally provided only longitudinal motion at the tip of the needle. In some procedures it would be desirable to have a handpiece that provides lateral motion as well.
Current phacoemulsification handpieces utilize different motions to emulsify the cataract. For example, a transverse motion of the needle may be used to emulsify the cataract and overcome some of the disadvantages of the traditional longitudinal motion. However, many surgeons prefer one type of motion over the other. Furthermore, phacoemulsification handpieces are expensive and several surgeons often share the same handpiece to save on costs. Thus it is desired to provide a removable horn that allows for different tips with the same handpiece. This would allow multiple surgeons to share the same handpiece, and each could use their preferred tips. This is much more cost-effective than purchasing entire separate handpieces for each surgeon.